Log/Log.cpp

#include "Log.h"

#include <chrono>   // date/time
#include <fstream>  // ofstream (logging to file)
#include <iomanip>  // std::put_time
#include <iostream> // std::ostream, std::cout, std::cin
#include <vector>   // list of outputs

namespace Log {

/*
 * abstract class Output
 *   default implementations
 */

// abstract base class for a log sink
class Output {
public:
	Output() {}
	Output(Level lvl_max) : lvl_max(lvl_max) {}
	virtual ~Output() {}

	virtual void log(Level lvl, std::stringbuf* sbuf) {
		std::ostream* os = getOs(lvl);
		if (os) {
			*os << sbuf << std::endl;
		}
	};

	virtual void setLogLevel(Level lvl) { lvl_max = lvl; }

protected:
	Level lvl_max = INFO;
	// returns the correct ostream for the given log-level
	// or returns nullptr if no ostream is set/enabled for this level
	virtual std::ostream* getOs(Level lvl) = 0; // abstract
};

// logging to stdout/stderr
class ConsoleOutput : public Output {
public:
	ConsoleOutput() : Output() {}

	virtual bool setColoredOutput(bool enabled) {
		// TODO: check the terminal's compatibility for colors
		coloredOutput = enabled;
		return true;
	}

private:
	std::ostream* osStd = &std::cout;
	std::ostream* osErr = &std::cerr;
	bool coloredOutput;

	virtual void log(Level lvl, std::stringbuf* sbuf) {
		//                                  OFF    FATAL    ERROR  WARN   NOTE   INFO   DEBUG TRACE
		static const char* color_codes[] = {"", "1;31;40m", "31m", "33m", "96m", "32m", "0m", "0m"};

		std::ostream* os = getOs(lvl);

		if (os) {
			// print colors if enabled
			if (coloredOutput)
				*os << "\x1B[" << color_codes[lvl] << sbuf << "\x1B[0m";
			else
				*os << sbuf;

			*os << std::endl;
		}
	}

	virtual std::ostream* getOs(Level lvl) {
		// out of scope?
		if (!lvl || lvl > lvl_max)
			return nullptr;

		// stderr for FATAL, ERROR, WARN
		if (lvl <= Level::WARN)
			return osErr;
		else
			return osStd;
	}
};

class FileOutput : public Output {
public:
	FileOutput(const std::string& filename, Level lvl_max)
	    : Output(lvl_max), filename(filename), ofs(filename, std::ofstream::out | std::ofstream::app) {}

	FileOutput(const std::string& filename, Level lvl_min, Level lvl_max)
	    : Output(lvl_max),
	      filename(filename),
	      ofs(filename, std::ofstream::out | std::ofstream::app),
	      lvl_min(lvl_min) {}

private:
	std::string filename;
	std::ofstream ofs;
	Level lvl_min = FATAL;

	virtual std::ostream* getOs(Level lvl) {
		if (lvl_min <= lvl && lvl <= lvl_max)
			return &ofs;
		return nullptr;
	}
};

static std::vector<Output*> outputs;

void log(Level lvl, std::stringbuf* strb) {
	for (Output* out : outputs) {
		out->log(lvl, strb);
		// reset stringbuffer read pointer to the beginning
		strb->pubseekpos(0);
	}
}

/*
 * class Entry
 */

Entry::Entry(Level lvl) : lvl(lvl) {
	addMetadataHeader();
}

Entry::~Entry() {
	log(lvl, ss.rdbuf());
}

void Entry::addMetadataHeader() {
	static const char* LevelTag[] = {"",         "[FATAL] ", "[ERROR] ", "[WARN ] ",
	                                 "[NOTE ] ", "[INFO ] ", "[DEBUG] ", "[TRACE] "};

	// get current date/time
	auto now          = std::chrono::system_clock::now();
	std::time_t now_c = std::chrono::system_clock::to_time_t(now);

	// datetime
	ss << "[" << std::put_time(std::localtime(&now_c), "%F %T") << "]";
	// log level
	ss << LevelTag[lvl];
}

void init() {
	// add default console logger
	if (outputs.empty())
		outputs.push_back(new ConsoleOutput());
}

void stop() {
	for (auto output : outputs)
		delete output;
	outputs.clear();
}

void addLogfile(const std::string& filename, Level max) {
	outputs.push_back(new FileOutput(filename, max));
}

void addLogfile(const std::string& filename, Level min, Level max) {
	outputs.push_back(new FileOutput(filename, min, max));
}

void setConsoleLogLevel(Level lvl) {
	outputs.at(0)->setLogLevel(lvl); // has to exist
}

void setColoredOutput(bool enabled) {
	((ConsoleOutput*) outputs.at(0))->setColoredOutput(enabled); // has to exist
}

LeveledSink::LeveledSink(Level level) : level(level) {}

} // namespace Log